1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to an image forming element for selectively adsorbing a toner for image formation. More particularly, the present invention relates to an image forming element and a manufacturing method thereof.
2. Description of the Related Art
FIG. 1 is a side view illustrating a structure of an image forming apparatus using a related art ring conductor, FIG. 2 is a schematic perspective view illustrating a related art image forming element, and FIG. 3 is an enlarged cross-sectional view illustrating a portion of the circumferential wall of the image forming element of FIG. 2. The image forming element shown in FIGS. 2 and 3 is disclosed in U.S. Pat. No. 6,014,157, which is incorporated herein by reference in its entirety.
Referring to FIGS. 1 through 3, the related art image forming apparatus includes a toner supply unit 40, an image forming element 10 to which a toner 1 is adsorbed from the toner supply unit 40 by an electrostatic force, a magnetic cutter 50 separating a part of the toner 1 adsorbed to the image forming element 10, and a toner return unit 60 that returns the toner 1 separated by the magnetic cutter 50 to the toner supply unit 40.
The toner supply unit 40 supplies the toner 1 from a toner storage unit 41 by using a toner supply roller 42. The image forming element 10 includes an image drum 12 and a plurality of ring electrodes 14 disposed on the image drum 12. Also, a control unit 16 is installed inside of the image drum 12 to individually apply a voltage to each of the ring electrodes 14. The magnetic cutter 50, which is able to separate the toner 1 adsorbed to the image forming element 10, is provided outside of the image drum 12.
In this structure, a part of the toner 1 transferred to the image forming element 10 from the toner supply unit 40 can be separated from the image forming element 10 through the magnetic cutter 50. The toner 1 remaining on the image forming element 10 can finally be transferred to a printing paper through an image transfer unit 70, and the printing paper is heated, thereby fixing the toner 1 to the printing paper.
However, the related art image forming apparatus has problems in that it is difficult and expensive to manufacture or repair the image forming element 10. Particularly, although the ring electrodes 14 of the image forming element 10 may be designed variously depending on required resolution, it is required that grooves having a width of approximately 20 μm should be formed uniformly at constant intervals of 42.3 μm on the image drum 12 to form the ring electrodes having a resolution of 600 dpi (dots per inch). Also, to electrically connect each of the ring electrodes 14 with the control unit 16, holes connected with each other should be formed inside and outside of the image drum 12 and should be filled with conductive materials, thereby complicating related manufacturing process steps. This increases the number of the manufacturing process steps, which are expensive and time consuming. As a result, printers made using the related art image forming apparatus have a high cost making popular acceptance for such printers difficult to achieve.
Furthermore, the related art image forming apparatus has problems in that it is difficult to manufacture the control unit 16 at a small size and thus the size of the image forming element 10 increases. Namely, the size of the control unit 16 increases as the control unit 16 should be provided with a certain packaging area in which a plurality of control chips are packaged to control the voltage applied to each of the ring electrodes. This reduces space utility inside the image drum 12 and increases the size of the image drum 12.
Accordingly, an image forming element and a manufacturing method thereof, in which a structure and manufacturing process steps can be simplified and a small size can be obtained is needed.